You can add the suffix (z)inho to pretty much any noun to form a diminutive usually expressing the idea that the thing is little or likeable. You can even add (z)inho to adjectives.
It is a different case with the suffix ola. People don’t usually make up new words with it as they do with (z)inho, and that is why it is new to you.
And most of the words that exist with ola aren’t simply smaller or likeable versions of their root word; often they’re not small at all, or particularly likeable. They typically have a meaning of their own, deserving their own entry in the dictionaries when their (z)inho siblings do not. Here are a few examples:
Rapazola is an older teenager.
Criançola is someone who's no longer a child but is more childish than we would like.
Bandeirola is a small flag used for signalling or showing boundaries of fields.
Galinhola is the name of several wild birds not related to the chicken.
Camisola is a nightdress in Brazil and a jersey, sweater in Portugal.
Portinhola (portinh(a) + ola) is indeed a small door, especially in a coach or a hatch in a ship.
Aldeola is indeed a small village.
Quintarola (quinta, farm, + ola) is a small farm.
I would say words with -ola will typically mean one or both of two things. One is that the thing is in some sense not the very best of its kind. For instance, an aldeola is a small aldeia; quintarola a small quinta; a criançola is the wrong type of ‘criança’; a graçola is not that funny.
Another possibility is that the thing is not bad or small at all, and the speaker, perhaps co-opting the previous notion, is simply trying to convey a light-hearted, somewhat playful attitude towards the thing. So it expresses some familiarity but not the sentimentality and ‘lamechice’ of the -inho word. This is the case of words such as cervejola and dentola, and that’s what I would infer if I heard made-up words such as in:
“Não queres comer esta bananola?” "Não, quero antes aquela maçãzola.”
“Vá, salta para a banheira: vamos lá lavar essa cabeçola!”
The two features may be combined in words such as festarola, jantarola; maybe not the best of their kinds, but we still like them.
Some derogatory epithets can take the suffix -olas too:
Sempre me saíste um doidolas!
És um bebedolas!
And the only example I can think of that derives from a verb (I can’t believe I had forgotten this crucial specimen):
Não passas dum cagarolas!
Some -ola words have meanings only tenuously related to the root word, and defy classification. For instance, castanhola is a musical instrument that looks vaguely like a castanha or chestnut. Camisola is not an inferior type of camisa, it is just a jersey whereas a camisa is a shirt. So when you come across a new -ola word it may be best to look it up in a dictionary: its meaning might not be guessable from the root word in a predictable way.
